Detergent products in the form of liquid are often considered to be more convenient to use than are dry powdered or particulate detergent products. Said detergents have therefore found substantial favor with consumers. Such detergent products are readily measurable, speedily dissolved in the wash water, capable of being easily applied in concentrated solutions or dispersions to soiled areas on garments to be laundered and are non-dusting. They also usually occupy less storage space than granular products. Additionally, such detergents may have incorporated in their formulations materials which could not withstand drying operations without deterioration, which operations are often employed in the manufacture of particulate or granular detergent products.
Although said detergents have a number of advantages over granular detergent products, they also inherently possess several disadvantages. In particular, detergent composition components which may be compatible with each other in granular products may tend to interact or react with each other. Thus such components as enzymes, surfactants, perfumes, brighteners, solvents and especially bleaches and bleach activators can be especially difficult to incorporate into liquid detergent products which have an acceptable degree of chemical stability.
One approach for enhancing the chemical compatibility of detergent composition components in detergent products has been to formulate nonaqueous (or anhydrous) detergent compositions. In such nonaqueous products, at least some of the normally solid detergent composition components tend to remain insoluble in the liquid product and hence are less reactive with each other than if they had been dissolved in the liquid matrix. Nonaqueous liquid detergent compositions, including those which contain reactive materials such as peroxygen bleaching agents, have been disclosed for example, in Hepworth et al., U.S. Pat. No. 4,615,820, Issued Oct. 17, 1986; Schultz et al., U.S. Pat. No. 4,929,380, Issued May 29, 1990; Schultz et al., U.S. Pat. No. 5,008,031, Issued Apr. 16, 1991; Elder et al., EP-A-030,096, Published Jun. 10, 1981; Hall et al., WO 92/09678, Published Jun. 11, 1992 and Sanderson et al., EP-A-565,017, Published Oct. 13, 1993.
A particular problem that has been observed with the incorporation of bleach precursor in non-aqueous detergents, include the chemical stability of the bleach precursor. EP 339 995 describes a non-aqueous liquid detergent composition comprising a persalt bleach and a precursor therefore, the composition containing a capped alkoxylated nonionic surfactant. EP 540 090 proposes to use a bleach precursor which is relatively insoluble in the non aqueous liquid phase of the liquid detergent composition.
A difficulty associated with the improvement of chemical stability of bleach precursor is that, upon dilution in the wash liquor, the bleach precursors still need to have a certain degree of solubility high enough to be effective as a bleaching species in the wash liquor.
Given the foregoing, there is clearly a continuing need to identify and provide nonaqueous, bleach precursor containing detergent compositions in the form of liquid products that have a high degree of chemical stability in the concentrate along with an efficient bleaching performance in the wash liquor.
Accordingly, it is an object of the present invention to provide a non-aqueous detergent composition wherein the bleach precursors have improved chemical stability in the concentrate, while at the same time still being effective as bleach species in the wash liquor.
According to the present invention, there is provided a nonaqueous detergent composition which is in the form of a liquid, containing a bleaching agent and a bleach precursor composition.